HEPOSA look at the Transformation

Between the ETRF and the Greek Reference Geodetic System

INF -2357

Vaios Balis – Christos Liapakis

Geotech Ltd

Projects’ identification Supervising authority:

KTIMATOLOGIO SA

“… responsible for the design, implementation and operation of the Greek Cadastral”

Projects: – HEPOS-SUPPLY– HEPOS-MEAS

Projects co-financed by the European Union under the operational programme “Information society”

HEPOS SUPPLY “Supply, installation and maintenance of the

fully operational and turnkey HEllenic POsitioning System – HEPOS”

Contractor: Trimble Europe B.V. Sub-contractors

– Geotech Ltd Site Location Installation Operation support

– OTENET SA Communication provider

HEPOS SUPPLY Reference stations: 100 (± 5) Duration of the project: 2 years Installation : 7 months

– Site location– Reference station installation– Control center installation – Communications

HEPOS SUPPLY

HEPOS SUPPLY 98 stations 2 networks 11 single RS

ETRF-2005

GGRS 87 Greek Geodetic Reference System 1987 Parallel to WGS 84

– Accuracy ~ 1 x 10-5

Origin offset from WGS– +199.723 m– -74.030 m– -246.018 m

Projection– Transverse Mercator– Central Meridian: 24º– Scale along central Meridian: 0.9996

HEPOS MEAS – Scope of the work “GPS measurements on control points of the

Greek National Triangulation Network and calculation of their coordinates in HEPOS reference system (ETRF 2005, epoch 2007.5)”

“Calculation of 7-parameter transformation from HEPOS reference system to GGRS 87 and vice versa”

Contractor: JV Ceotech – Topomet Duration : 10 months !!!!

Points to be measured How many points per 1:50000 scale map sheet ?

1:50000 scale map sheet

~ 28 km

~ 22 km

1:50000 scale map sheets How many 1:50000 map sheets ?

Total number of points How many points ?

– 8 per each map sheet 1:50000 scale– 387 1: 50000 scale map sheets– or roughly 2800 points to be measured

Specifications– L1/L2 GPS receivers– Occupation time: 1 hour– Logging interval: 15 sec– Elevation mask : 15º– 6 satellites tracked : 90% of session time – PDOP < 4 : 75% of session time– 1 Primary base station – REF (24 hours logging)– 1 Secondary base station – SEC (logging until all 8

points of the map sheet have been measured)

GPS measurements

Resources 10 survey crews 2 people per survey crew 5800 L1/L2 receivers with ACU Handheld GPS for Guidance Cameras for documentation 4 WD for transportation Daily data transfers to the office 3 months field work 9 months office work

Pre-survey office work

Some measured points

Some non measured points

Total measured points

2470 points

Measured point documentation

TGO projects

128 TGO projects

7 parameter transformation TTC SW

Transformation residuals

•Transformation accuracy 1:50000 scale map sheets

– Horizontal Mean value = ± 3 cm Max Value = ± 5 cm

– Vertical Mean value = ± 6 cm Max Value = ± 8 cm

•Transformation accuracy 1:100000 scale map sheets

– Horizontal Mean value = ± 6 cm Max Value = ± 9 cm

– Vertical Mean value = ± 10 cm Max Value = ± 17 cm

7 parameter transformation (global)

TTC SW

Residuals

Residuals – North Greece

Residuals - Islands

Residuals – West Greece

Residuals – Central Creece

Residuals – North East Greece

Shift grid files

Shift grid files

Geoid

Accuracy

HEPOS vs GGRS'87 (m)

0,037 -0,040 -0,031

0,014 -0,050 0,012

-0,007 -0,049 0,009

0,017 -0,033 -0,035

0,028 -0,028 -0,037

0,022 -0,025 -0,039

0,017 -0,055 -0,006

0,010 -0,046 -0,029

0,017 -0,041 -0,020

Survey controller application

C:\Documents and Settings\ccyrus\Desktop\INF-2357\Trimble Survey Controller 12.10 Emulator\survey.exe

Thank you for your attention…

Questions